You can use a GUIContent which can contain both, or in a BeginHorizontal() you could draw one label with an image and one with the text of the score, then EndHorizontal().
public Texture2D icon; //set this in the inspector or whatever
void OnGUI()
{
//screen point to start drawing
Vector2 startPoint = new Vector2(10, 10);
//the gap between each GUI draw call
float gap = 10;
//strings for who killed who
string killer = "Player";
string killed = "Player";
//get the number of pixels (up & down) each string will take on screen
Vector2 killerSize = GUI.skin.label.CalcSize(new GUIContent(killer));
Vector2 killedSize = GUI.skin.label.CalcSize(new GUIContent(killed));
//create rects for our strings and icon
Rect killerRect = new Rect(
startPoint.x, //starts at the begining
startPoint.y,
killerSize.x,
killerSize.y);
Rect iconRect = new Rect(
startPoint.x + killerSize.x + gap, //starts after previous rect + a small gap
startPoint.y,
icon.width,
icon.height);
Rect killedRect = new Rect(
startPoint.x + killerSize.x + icon.width + gap * 2, //starts after previous rect + a small gap
startPoint.y,
killedSize.x,
killedSize.y);
//draw each
GUI.Label(killerRect, killer);
GUI.DrawTexture(iconRect, icon);
GUI.Label(killedRect, killed);
}